In a communications system, a state of a channel from a base station to user equipment decides a size of a throughput from the base station to the user equipment. An index measuring the channel state is a modulation coding scheme (MCS) level that can be supported. A better channel state indicates a higher supported MCS level, and a worse channel state indicates a lower supported MCS level. In a mobile communications system, affected by mobility and an environment of user equipment, a channel from a base station to the user equipment is changeable, and therefore a supported MCS level is also changeable. In a relatively bad channel state, if a relatively high MCS level is used during data transmission, a resulting frame error rate is relatively high, which does not satisfy any index requirement of the system. In a relatively good channel state, if a relatively low MCS level is used during data transmission, a throughput from a base station to user equipment is affected, thereby affecting a throughput of the system. Therefore, in a mobile communications system, an adaptive modulation and coding (AMC) method is generally used, so that an MCS Level applicable to a link from a base station to user equipment is adaptively adjusted according to a state of a channel from the base station to the UE, thereby optimizing the system throughput. An MCS level may be determined based on an MCS table and a transport block size (TBS) corresponding to the MCS level needs to be determined based on a TBS table.
The presented embodiments provide system and method to determine an MCS level and a TBS based on an MCS table and a TBS table, so as to maximize frequency spectrum efficiency.